Replacing adenoviral vector HVR1 with a malaria B cell epitope improves immunogenicity and circumvents preexisting immunity to adenovirus in mice
Takayuki Shiratsuchi, Urvashi Rai, Anja Krause, Stefan Worgall, Moriya Tsuji
Takayuki Shiratsuchi, Urvashi Rai, Anja Krause, Stefan Worgall, Moriya Tsuji
View: Text | PDF
Research Article Infectious disease

Replacing adenoviral vector HVR1 with a malaria B cell epitope improves immunogenicity and circumvents preexisting immunity to adenovirus in mice

Abstract

Although adenovirus (Ad) has been regarded as an excellent vaccine vector, there are 2 major drawbacks to using this platform: (a) Ad-based vaccines induce a relatively weak humoral response against encoded transgenes, and (b) preexisting immunity to Ad is highly prevalent among the general population. To overcome these obstacles, we constructed an Ad-based malaria vaccine by inserting a B cell epitope derived from a Plasmodium yoelii circumsporozoite (CS) protein (referred to as the PyCS-B epitope) into the capsid proteins of WT/CS-GFP, a recombinant Ad expressing P. yoelii CS protein and GFP as its transgene. Multiple vaccinations with the capsid-modified Ad induced a substantially increased level of protection against subsequent malaria challenge in mice when compared with that of unmodified WT/CS-GFP. Increased protection correlated with augmented antibody responses against the PyCS-B epitope expressed in the capsid. Furthermore, replacement of hypervariable region 1 (HVR1) of the Ad capsid proteins with the PyCS-B epitope circumvented neutralization of the modified Ad by preexisting Ad-specific antibody, both in vivo and in vitro. Importantly, the immunogenicity of the Ad-containing PyCS-B epitope in the HVR1 and a P. yoelii CS transgene was maintained. Overall, this study demonstrates that the HVR1-modifed Ad vastly improves upon Ad as a promising malaria vaccine platform candidate.

Authors

Takayuki Shiratsuchi, Urvashi Rai, Anja Krause, Stefan Worgall, Moriya Tsuji

×

Figure 3

Transduction ability, productivity, and genetic stability of capsid-modified rAds.

Options: View larger image (or click on image) Download as PowerPoint
Transduction ability, productivity, and genetic stability of capsid-modi...
(A) P. yoelii CS protein expression after capsid-modified rAd infection of HeLa cells. Whole cell lysates were prepared 24 hours after infection, and P. yoelii CS protein expression was analyzed by Western blotting. P. yoelii CS protein was detected with mouse monoclonal anti–P. yoelii CS antibody (9D3). Lane 1, HeLa (uninfected); lane 2, WT/CS-GFP; lane 3, B-Fib/CS-GFP; lane 4, B-HVR1/CS-GFP; lane 5, B-HVR5/CS-GFP; lane 6, B-HVR1/B-Fib/CS-GFP. (B) Productivity of capsid-modified rAds. Infectious units of the crude Ad solutions prepared from single-round infection of AD293 cells were determined using end point dilution method. Data are shown as mean ± SD for triplicate wells. (C) Stability of the inserted PyCS-B epitope sequence in Ad genome after Ad passages. 5 × 105 AD293 cells in 24-well plates were infected with 1 × 108 v.p. of capsid-modified rAd, and crude Ad solution was prepared by freeze-thaw cycles 2 days after infection. One-tenth of the crude virus solution was used for the next round of infection. Ad genome corresponding to HVR1, HVR5 of the hexon, or HI loop of fiber was amplified by PCR, using crude Ad solutions as templates after indicated passage of capsid-modified rAds. P5, P10, and P15 represent crude Ad solutions after 5, 10, and 15 passages, respectively. M, 1-kb plus marker (Invitrogen). Lane 1, WT/CS-GFP; lane 2, B-HVR1/CS-GFP; lane 3, B-HVR5/CS-GFP; lane 4, B-Fib/CS-GFP; lane 5, B-HVR1/B-Fib/CS-GFP.